There was a hard frost last night that killed the dahlia tops. I’m going out of town and won’t have a chance to dig up the roots for at least a week. Is that too late to save them?
For the tuberous roots of dahlias to be damaged, the soil would have to freeze several inches deep — something that usually doesn’t happen until a month or two after the first frost. (In USDA Plant Hardiness Zones 8 and warmer, it may not happen at all.) So you can delay this task a few weeks without worry.
Here’s my technique for storing tender bulbs, including dahlias and cannas, through the winter. Caladiums, tuberous begonias, elephant ears, and gladiolus prefer a slightly warmer storage temperature of around 50°F. —Doug Hall